Grinding or honing device



Filed Feb. 3, 1951 A M Ma 4 m I j E 2 m a x. v 5 1 J J34 u III /%B a 942 m u a Q .1... m 2

Patented Sept. 7, 1954 UNITED STATES PATENT OFFICE GRINDING 0R HONINGDEVICE Robert S. Taylor, Detroit, Mich.

Application February 3, 1951, Serial No. 209,223

13 Claims. 1

This invention relates to abrading or honing tools and more particularlyto improvements in the adjustment of the honing elements and in themethod of effecting such adjustments.

It has been the common practice heretofore to provide a circularlyspaced set of abrading elements on a rotating and axially movable headfor finish grinding bores and to provide hydraulic pressure foreffecting radial expansion of the honing elements into engagement withthe bore. Considerable difiiculty has been encountered in controllingthe exent of radial movement of the honing elements to stop theirgrinding operation at the desired diameter of the bore. Some attemptshave been made to provide automatic means for controlling the movementof the honing elements. For such purpose a controlling fluid suppliedunder constant pressure has been suggested which vented or dischargedonto the wall of the bore and utilized the drop in pressure resulting asthe bore enlarged to control the extent of radial movement of the honingelements.

Such control mechanism required a large and complicated number of partsincluding electrical circuits and switches and was not satisfactorilyaccurate under all conditions.

An important object of the present invention is to provide an improvedmethod of and means for controlling the extent of radial movement of theabrading or honing elements and to accomplish this operation in anaccurate and automatic manner with a minimum number of parts. Anotherimportant object of the invention is to provide an improved tool forhoning and grinding but also adaptable for reaming and the like which isa self-contained hydraulically operated unit attachable to anddetachable from a machine and is self-operable to determine the limitsof the grinding or cutting operation for which it is designed. A furtherimportant object of the invention is to provide an improved honing tooland the like which is constructed in a novel man ner to contain a bodyof fluid for radially moving the abrading or cutting elements and asecond body of fluid for controlling the operation of the first fluidbody, the second body of fluid being sealed in a novel manner in theoperating head of the tool and being provided with novel means forvarying its controlling action on the first fluid.

The invention is herein illustrated as applied to grinding or honingtools but it is to be understood that the operating and controllingfeatures of the invention are applicable to other types of tools such ascutting and reaming devices. In one illustrated embodiment of theinvention a fluid under pressure is utilized to advance the abradingelements into engagement with the wall of a bore in a workpiece.Although such operating fluid may be supplied from an outside sourceassociated with the machine to which the tool is attached, it ispreferred that the fluid be confined within a relatively sealed chamberincorporated in the tool and that the tool be provided with variablemeans for building up the pressure of the fluid to the desired amountfor actuating the abrading elements. Also incorporated in the head ofthe tool are novel sizing elements which are radially movable with theabrading elements to maintain continuous contact with the surface beingground. Associated with these sizing elements and responsive to thepositions assumed thereby is a novel control means for governing theaction of the fluid acting on the honing or abrading elements.Preferably this control means is a second body of fluid sealed underregulatable pressure within the tool. This second body of fluid servesto couple the sizing elements with valve means controlling the action ofthe first fluid body on the abrading elements. Preferably the two fluidsare liquids, such as thin oil, and arranged to oppose one another intheir action on the valve means.

In another illustrated embodiment of the invention solid matter in theform of small spheres are used in the same manner as the fluidspreviously mentioned for controlling the action of the abradingelements.

Various other objects, advantages and meritorious features of theinvention will become more fully apparent from the followingspecification, appended claims and accompanying drawings wherein:

Fig. 1 is a view, partly in longitudinal section and partly inelevation, of a honing tool embodying features of the invention,

Fig. 2 is a cross sectional view through the tool of Fig.1 taken alongline 2-2 thereof,

Fig. 3 is a cross sectional View taken along line 33 of Fig. 1, and

Fig. 4 is an enlarged fragmentary sectional view taken through the headportion of a honing tool illustrating a modification of the invention.

Referring particularly to the drawing. the honing tool illustratedtherein is adapted to be attached to a part in the machine which isrotatable and axially movable while rotated. While so rotated, theabrading elements of the tool will grind the wall of a bore of aworkpiece into which the tool extends. The tool, in general, comprises alower working head H) which enters the bore and an upper end section l2which is attached to the machine part.

The working head carries one or more honing sticks or stones N, therebeing four shown in the illustrated embodiment of the invention, whichare equally circularly spaced apart around the axis of the head as isevident in Fig. 2. The body portion of the head is preferably exteriorlycylindrically shaped and of a diameter slightly less than that of thebore size for which it is intended in order to freely enter the bore.Cut or otherwise formed in the exterior surface of the head ID are aplurality of longitudinally extending grooves l6 corresponding in numberto the number of honing stones employed and shaped to receive the honingstones. Four such grooves are shown in the present embodiment of theinvention, one for each honing stone. Each honing stone I4 is capable ofradial movement in its respective groove as will be explained more fullyhereinafter.

Also carried by the head ID of the tool are one or more sizing elementsor pins [6 which are operable to engage the wall of the bore and controlthe functioning of the tool. Four such sizing pins are shown in theillustrated embodiment of the invention and they are equally circularlyspaced apart from one another and angularly offset to the grooves I6 soas to be disposed therebetween. The pins l8 may be cylindrical information as shown and disposed on a transverse plane preferablyintermediate the opposite ends of the honing sticks M on the sectionline 22 of Fig. 1. The outer ends of the pins may have carboloy ordiamond inserts for contact with the wall of the bore being ground.

The head ll! of the tool is axially bored out to provide a series ofcommunicating passages and chambers of various dimensions. In the areaof the honing sticks M the head H! is provided with an elongated chamberadapted to contain a controlling medium such as a body of fluid. Thelower end of the chamber I6 opens out through the forward end of thehead and is closed by means of an adjustable cap as will be more fullyexplained hereinafter. The opposite or upper end of the chamber 20 isreduced in size to form a short section 22. Located in this shortpassage section is a pin 24 preferably tapered at its upper end whichsealingly fits within the passage but is capable of axial traveltherein. The short passage 22 opens into a wider chamber 26 wherein avalve means in the form of a ball check valve 28 is disposed. A coiledspring 30 also in the chamber 26 urges the ball valve to a seatingposition.

In the illustrated embodiment of the invention, the ball valve 28 andits spring 36 are supported in an assembly of elements in the chamber 26including a relatively long sleeve 32 fitting the chamber and occupyingthe major portion of the lower half thereof. Telescopingly receivedwithin the lower end of the tube is a retainer 34 for the ball valveincluding a transverse wall 36 having a central chamfered aperturetherethrough for seating the ball valve. The transverse wall extendsbeyond the part of the retainer entering the sleeve 32 to form aperipheral shoulder upon which the lower end of the sleeve rests. Thetransverse wall 36 may be spaced from the lower end of the chamber 26 bya ring-shaped member 38 as shown in Fig. 1. The relationship of theparts in the lower portion of the chamber 26 is such that the taperedend of the pin 24 is disposed closely adjacent to the ball valve and iscapable of unseatin the same and opening the aperture through thetransverse wall 36 in a manner hereinafter described.

Located in the upper half portion of the chamber 26 is a member 40 ofresilient material having a narrow axial duct 42 therethrough openingout through the opposite ends thereof. The upper end of the sleeve 52may be shaped with a cup-shaped recess to receive and support the lowerend of the member 46 in the manner shown in Fig. l. The axial duct inthe member 46 communicates through a narrow passage in the upper end ofthe sleeve 32 with the interior thereof. The upper end of the resilientmember so projects beyond the upper end of the chamber 26 and enters arelatively large cavity 4 in the upper end of the head 18. Ashereinafter described the upper projecting end of the resilient member40 cooperates with a universal joint coupling the head to the uppersection [2 of the tool.

The axial duct 42 of the resilient member 40 communicates at its upperend with the bore 46 of a hollow shaft 58 constituting a part of theupper section I2 of the tool. In the embodiment of the inventionillustrated herein the bore 46 of the shaft serves as a chamber forcontaining the major portion of a second body of fluid which ashereinafter described communicates with the bases of the grooves IS inwhich the honing sticks M are received to force the latter radiallyoutward from the head.

The bottom portions of the grooves 16 in which the honing sticks aremounted communicate with the lower end of chamber 26 to receive fluidunder pressure. This is accomplished as shown in the illustratedembodiment of the invention by means of small inclined ducts or passages50, one for each groove, which converge toward one another and openthrough the lower end wall of the chamber 26. The passages 56 divergeaway from one another as they lead to their respective grooves and openinto the latter under the honing stick it received therein. Each honingstick is supported on a sealing member 52 which extends across thebottom of the honing stick as shown in Fig. 2. Each groove is providedwith a shallow channel 54 in the base thereof extending longitudinallythe full length of the groove and having a width slightly less than thatof the groove as shown in Fig. 2. The shallow channel of each grooveprovides a clearance between the bottom face of the sealing member andthe bottom of the channel into which the fluid under pressure fromchamber 26 is delivered.

As previously mentioned, the elongated chamber 20 in the lower endsection of the head 10 contains a medium such as a body of fluid whichwhen the tool is in operation is under pressure. This fluid acts on theinner ends of the sizing elements or pins I8 and urges the same radiallyoutwardly of the head 10. Each sizing pin is slidably fitted into aradial bore 56 of the head and the outer end section of the pin normallyprojects beyond the peripheral surface of the head 10 as shown in Fig.2. Each pin I8 is connected by a reduced neck portion to a plunger 58which works in the inner end of its bore 56 in which the pin isreceived. Suitable sealing means may be provided around the neck portionof each pin to prevent leakage of fluid. The inner end of each plungermay be arcuately shaped to conform to the curvature of the wall of thechamber 20, as shown in Fig. 2. The inner curved ends of the plungersare exposed to the '5 body of fluid contained within the chamber 20 andit is evident that when pressure is built up in the fluid body that itwill cause the plungers and the sizing pins connected thereto to moveoutwardly radially in their respective bores.

As previously mentioned, the lower end of the upper part it of the toolis received in the cavity 44. The hollow shaft it is provided on itslower extremity with a spherical ball-shaped end section 68 whichconstitutes a part of a universal joint. Carried by the spherical endsection are one or more locking balls 62 which drivingly couple theshaft to the head I!) of the tool. For this purpose the inner wall ofthe cavity 44 is provided with grooves St in which the balls 62 arepartly received, as illustrated in Fig. 3. In this manner the shaft itis drivingly coupled to the head EU for joint rotation, yet permittingthe head if) to have limited universal movement relative to the shaft toaccommodate itself to any misalignment of the tool in the bore to beground. The upper end of the cavity 44 is closed by an externallythreaded sleeve 66 which is threaded in the upper section of the cavity.As shown, the sleeve 66 has an internal diameter slightly greater thanthe external diameter of the shaft 43 to provide a clearancetherebetween for permitting a limited angular movement of the latter.The sleeve 66 is locked in place by a ring 68 threaded thereto andabutting the upper end of the part ii].

To provide communcation between the chamber 46 and the axial duct #2 ofthe resilient member All as well as to receive the upper end of thelatter, the spherical part 66 of the universal joint is provided with anaxial passage i therethrough. This passage is wider at its lower end andreceives the upper end of the resilient member All. In the uppernarrower portion of the passage there is threadedly received a nippleF2. The nipple extends downwardly into the wider portion of the passageand is provided with a conical shaped head which seats on the upper endof the resilient member 40 in the manner shown in Fig. 1. The passagethrough the nipple provides communication between the chamber 46 and theaxial duct of the resilient member Mi. The flexible character of. theresilient member enables it to follow any angular displacement of theupper and lower sections of the tool while maintaining fluid tightcommunication between the chambers 26 and 46.

Although the chamber 46 formed by the hollow interior of the shaft 48may communicate with an outside source of fluid under pressure, it ispreferred to confine the fluid body wholly in the tool and provide meansincorporated in the tool for building up pressure on the fluid body. Forthis purpose a plunger M is reciprocatingly disposed in the hollowinterior of the shaft and cooperates with the wall thereof to close thechamber 4t at its upper end. The plunger is joined to a rod 76 ofreduced dimension which extends upwardly and is connected to mechanismfor shifting the plunger axially in the hollow shaft.

It is preferred to use incompressible fluids for either one or both ofthe fluids contained in the chamber and in the chamber 46 and thepassages leading therefrom. Suitable fluids for this purpose are eitherlight or heavy oils for lubricating or hydraulic uses. It is thusunderstood that in one desirable operating arrangement the chamber 20contains a body of oil or like liquid and the chamber 46 and itsconnecting passages contains a second body of oil or like liquid. Thetwo liquid bodies are kept separate from one another and one controlsthe action of the other, as hereinafter described.

The mechanism for moving the plunger 14 in the hollow shaft may be ofany suitable means, but is herein shown as comprising an externallythreaded sleeve 78 to Which is threadedly connected a surrounding collar80. The hollow shaft 48 is provided above the plunger with diametricallyopposed longitudinal slots, one of which is shown at 52 through which across pin 84 extends. The cross pin 84 is free to move up and down theslots and its intermediate portion is fixed to the plunger rod 16 andits opposite ends are received in and secured in the sleeve 18 for jointtravel therewith along the shaft.

Yieldingly urging the collar and the sleeve l8 downwardly is a coiledspring 86 encircling the upper end of the shaft 18. The lower end of thecoiled spring 86 seats on an annularly shaped member or washer 88 andthe opposite end thereof seats on a member 90 shaped in any suitablemanner for driving connection to the machine upon which the tool ismounted. The washer 88 has a circular dimension such that it bears uponthe upper end of the collar 8|], as shown in Fig. l, and by virtue ofthe tension of the spring 86 it exerts a yielding force tending to drivethe collar 80 downwardly on the shaft 48. Since the collar is coupled tothe sleeve 18 and the latter is connected to the plunger rod 16 by meansof the cross pin 84, the force exerted by the spring 86 is conveyed tothe plunger i l causing the latter to exert pressure on the confinedfiuid in the chamber 46. The pressure exerted by the plunger 14 iscapable of adjustment by threadedly rotating the collar 80 relative tothe sleeve 18. The engaging threads of these two members will shift theplunger 14 either downwardly or upwardly depending on the direction ofthe relative rotation of the collar. Thus, the pressure exerted by theplunger 14 on the confined fluid in the chamber 46 may be convenientlyadjusted by rotation of the collar 80 relative to the sleeve 18.

The ball valve 28 in its closed position, as shown in Fig. 1, functionsto cut off delivery of the fluid for moving the honing sticks I 4radially outwardly. The aperture in the transverse wall 38 upon whichthe ball seats is complementary to the curvature of the ball so that inthe fully seated position of the ball it completely cuts off the flow offluid from the chamber 26 to the ducts 50. The pointed end of the pin 24in the short narrow passage section 22 normally bears against the ballvalve 28 in its closed position, as shown in Fig. 1. Upon upwardmovement of the pin 24 from the position shown in Fig. 1, it will liftthe ball valve 23 and unseat it. This will open the aperture in thetransverse wall 38 and permit fluid in the chamber 26 to flow therefromthrough the ducts 50 to the bases of the grooves Hi. It is thus apparentthat when the ball valve is unseated and pressure is built up in thefluid in the chamber t6, such as exerted by the plunger 74, it willforce the fluid through the duct 42 of the flexible member 40 and thenceby chamber 26 and the ducts 56) to the bases of the grooves where thepressure will force the honing sticks M- outwardly relative to the head[0.

The delivery of pressure to the honing sticks will only occur when theball valve 28 is unseated by the pin 24. The movement of the latter isgoverned by the pressure of the controlling medium or fluid in thechamber 20. If the pressure in the chamber 20 is suflicient to overcomethat of the fluid in the chamber 46 and the valve spring 30 it will movethe pin 24 upwardly and unseat the ball valve, thereby allowing fluid toflow through the ducts 50 to the honing sticks. The two fluid bodies arekept separate from one another by the pin 24, the latter being incapableof traveling sufliciently to permit the fluid confined in the chamber 20from entering the chamber 26. When the pressure of the fluid in thechamber 48 is greater than the pressure of the fluid in the chamber 20it will force the ball valve downwardly and cause it to fully seatthereby cutting off the delivery of fluid to the bases of the grooves inwhich the honing sticks 24 are located.

The pressure of the fluid in the chamber 20 is controlled by means of anadjustable cap located in the lower or forward end of the part H! of thetool. As shown in Fig. l, the adjustable cap comprises an externallythreaded member 92 having a slightly enlarged head 94 at its base orouter end and a plunger 96 projecting from its opposite or upper end.The enlarged head 94 is provided with a slot or any other suitable meansto which a tool may be applied for rotating the member 92 to vary theextent the plunger 96 projects into the chamber 28. In one direction ofits rotation, the member 92 will move the plunger 96 upwardly in thechamber 20 increasing the pressure of the fluid contained therewithinand causing the pin 24 to move upwardly and unseat the ball valve 28. Itis obvious that rotation of the member 96 in the opposite direction willretract the plunger 96 and reduce the pressure or" the fluid confinedwithin the chamber 26.

In the operation of the device, the fluid in the chamber 29 which actson the plungers 58 of the sizing pins i8 is initially adjusted to thedesired amount to shift the plungers to the desired diameter of the boreto be ground. This may be accomplished, for example, by inserting thehead ill of the tool into a bore of a gauge having the precise diameterto which it is desired to grind the bore of a workpiece. While in thegauge the cap 92 is adjusted to build up pressure on the confined fluidin the chamber 2! suflicient to project the sizing pins outwardly intoengagement with the wall of the gauge bore without, at the same time,unseating the ball valve 28 and allowing the second fluid body toradially expand the honing sticks, Thereafter, the head H) of the toolis inserted into the bore of a workpiece to be ground. Since this boreis of less diameter than that for which the sizing pins have been set,the latter will be compressed or forced radially inwardl by engagementwith the bore. Since the confined liquid in the chamber 20 isincompressible, the only element which is movable to allow the sizingpins to collapse is the pin 24. This will move upwardly and unseat thevalve and expose the entrance ends of the ducts 50 to the fluid confinedin the chambers 26 and 46.

After the tool is inserted into the bore to be ground, the collar as isthreadedly adjusted to cause the plunger 'M to exert pressure on thefluid confined in the chamber 46. Since the valve 2% is unseated, thefluid confined in the chamber 46 is permitted to move downwardly throughthe passages leading to the bases of the honing sticks and will forcethe honing sticks radially outwardly and into engagement with the boreto be ground. As the bore of the workpiece is ground, the

pressure of the fluid in the chamber 28 causes the sizing pins [8 tomove outwardly with the honing sticks and maintain continuous contactwith the Wall of the bore. As the sizing pins move outwardly in theirrespective passages during the grinding or honing operation, they permitthe fluid confined in the chamber to follow their movement, therebyreducing the pressure acting on the pin 24. When the sizing pins reachthe diameter for which they were initially set, the pin 24 will havetraveled downwardl sumciently to bring the ball valve 28 into seatedposition where it will cut oil? further delivery of fluid through theducts st to the bases of the honing sticks [4. This will automaticallyprevent further outward radial movement of the honing sticks and stoptheir grinding operation even though the tool continues to rotate. Ifthe bore to be ground is deep and the tool is axially moved into anunground section, the sizing pins will be slightly collapsed causing thevalve to unseat and the operation of grinding the bore may be continuedwithout the necessity of any adjustment of the tool.

A modification of the invention is shown in Fig. 4 wherein, in lieu of afluid medium in the chamber 25% for controlling the movement of thesizing pins Hi, there are provided a plurality of solid elements in theform of spherical members or balls 88. These balls are compactlyarranged in the chamber 23 and such that at least one ball is positionedin each sizing pin here as and acts on the inner end of the sizing pin.In the center of the chamber 29 opposite the entrances to the sizing pinbores a clearance is provided between the balls as is evident in Fig. l.As the series of balls in the chamber 22 are compressed by forces actingon either or both ends thereof this clearance is reduced and the ballsin the sizing pin bores are forced radially outwardly and project theirrespective sizing pins beyond the external diameter of the head It.Adjustment means similar to that described in connection with Fig. 1 maybe employed to exert a compressive force on the balls from the lower endof the head Hi. This adjustable feature includes a plunger I00corresponding to plunger 98 previously described but may be longer thanthe latter to project further into the chamber 20. At the opposite endof the series of balls in the chamber 20 and bearing thereagainst is thebase end of a pin I02 corresponding to the valve unseating pin 22previously described. The action and operation of the balls 98 issimilar to that of the fluid body for which they are substituted andradially shift the sizing pins i8 outwardly or inwardly depending uponthe compressive forces acting on the balls.

What I claim is:

1. In a device for honing out bores, a rotatable body, a plurality ofradially movable honing stones carried by the body in circularly spacedrelation therearound and movable into engagement with the bore to beground, a plurality of radially movable sizing elements carried by thebody in circularly spaced relation therearound and movable intoengagement with the bore to be ground, separate fluid pressure means formoving said honing stones and said sizing elements into en gagement withthe bore to be ground, and means responsive to the pressure of the fluidmeans for moving the sizing elements and operable to limit the action ofthe fluid pressure means for moving the honing stones.

2. In a grinding or honing device, a rotatable body, a plurality ofabrading members carried ing moved outwardly from the body for engage'ment with the wall of a bore in which the body is inserted, forceexerting means for acting on the element to shift the same outwardly ofthe body to maintain continuous contact with the wall of the bore as itis being ground, means for regulating the extent of the outward movementof said element and for limiting its outward movement to a desiredposition, and means responsive when said element reaches said limit ingposition for discontinuing the application of the force exerting meansacting on the abrading members.

3. In a grinding or honing tool, a rotatable body, a plurality ofabrading members carried by v the body in circularly spaced relationaround the axis of rotation thereof and capable of being moved radiallyoutwardly of the body for engagement with the wall of a bore in whichthe body is inserted, means for delivering fluid under pressure to theabrading members to shift the same outwardly into engagement with thewall of a bore in which the body is inserted, a plurality of sizingelements carried by the body in circularly'spaced relation around theaxis of rotation thereof and capable of being moved sub-' stantiallyradially outwardly of the body for engagement with the wall of a bore inwhich the body is inserted, means for exerting pressure on the sizingelements to shift the same outwardly of the body to maintain continuouscontact with the wall of a bore bein ground by the abrading members,control means for limiting the extent of the outward movement of thesizing pins, and valving means for controlling the operation of saidfluid pressure delivery means and operatively connected to the sizingelements so as to substantially cut off the fluid pressure deliverymeans when the sizing elements reach the controlled extent of theiroutward movement.

4. In a grinding or honing tool, a rotatable body, a plurality ofabrading members carried by the body in circularly spaced relationaround the axis of rotation thereof and capable of being moved radiallyoutwardly of the body for engagement with the wall of a bore in whichthe body is inserted, means for delivering fluid under pressure to theabrading members to shift the same outwardly into engagement with thewall of a bore in which the body is inserted, a plurality of sizinelements carried by the body in circularly spaced relation around theaxis of rotation thereof and capable of bein moved substantiallyradially outwardly of the body for engagement with the wall of a bore inwhich the body is inserted, means for exerting pressure on the sizingelements to shift the same outwardly of the body to maintain continuouscontact with the wall of the bore being ground by the abrading members,said pressure exerting means progressively decreasing in pressure as thesizing elements move outwardly, and control means for cutting off theflow of fluid in said fluid pressure delivery means and responsive tosaid pressure exerting means, said control means being operable to cutoff the flow of fluid in said fluid pres- 10 sure delivery means whenthe pressure of said pressure exerting means falls below a certainlevel.

5. In a grinding device, a rotatable body adapted to carry an expandibleand contractible abrading member, fluid pressure responsive means forexpanding the abrading member, a source of pressure fluid communicatingwith said fluid pressure responsive meansQvalve means movable to open orclose the communication between said source and said fluid pressureresponsive means, an outwardly movable measuring element carried by thebody for contacting the surface engaged by the abrading member, meansfor maintaining said element in continuous contact with the surfaceengaged by the abrading member, means rendering the valve meansresponsive to the movement of the measuring element and causing thevalve means to move to closed position when the measurin element hasmoved a certain extent of its outward movement, and means for modifyingsaid last means to regulate the extent of outward movement of themeasuring element before the valve means moves to closed position.

6. In a grinding tool having a body and an abrading member mountedtherein for movement outwardly relative to the body, means responsive tofluid pressure for moving the abrading member outwardly from the bodyand into engagement with a surface to be round, means for deliveringfluid under pressure to said fluid pressure responsive means for movingthe abrading member outwardly relative to the body, a valve forcontrolling the flow of fluid through said fluid delivery means, ameasuring element mounted in the body and projecting outwardly therefromfor contact with the same surface engaged by the abrading member andoperable to measure changes in the level of the surface engaged by theabrading member, and means operatively connecting the measuring elementwith the valve and effective to vary the flow of fluid through saidfluid delivering means in response to changes in the level of thesurface engaged by the abrading member.

7. In a metal working device, a tool fordoing work upon a work piece,fluid pressure means for urging the tool toward and into engagement witha work piece and includingla fluid pressure delivery conduit and a valvein the conduit, a measuring instrument for controlling the operation ofthe tool, means for continuously urging the measuring instrument intocontact with the surface of the work piece engaged by the tool, saidmeans including a pressure chamber the pressure of which varies inaccordance with changes made in the surface of the work piece engaged bythe tool, and means responsive to such variations in pressure andoperatively connected to said valve to control the valve and therebyvary the fluid pressure delivered by said conduit for urging the toolinto engagement with the work piece.

8. In a surface grinding device, an abrading member for grinding asurface, fluid pressure means operable to urge the member toward andinto engagement with the surface to be ground and including a fluidpressure delivery conduit and a valve in the conduit, a measuringinstrument for controlling the operation of the abrading member, meansfor continuously urging the measuring instrument into contact with thesurface being ground, said means including a congrinding an adjacentsurface, fluid pressure responsive means in the body for moving theabrading members outwardly of the body, means for delivering fluid underpressure to the body and into communication with said fluid pressureresponsive means, valve means in said delivery means and controlling theamount of fluid under pressure delivered thereby, said body having atleast one outwardly opening recess, a sizing element in each recess andmovable outwardly of the recess for engagement with the surface being'gr'ound, said body having a chamber communicating with the base of eachrecess, a substantially incompressible mobile medium in said chamber andentering each of said recesses for contacting the sizing elements andfor following the siz ing elements as they move outwardly in response'to changing levels of the surface bein ground, and means operativelyconnected to said valve and to the incompressible mobile medium andresponsive to the movement of the latter resulting from the movement ofthe sizing elements for moving the valve and thereby varying the amountof fluid pressure acting on the abrading members.

10. In a surface grinding device, an abrading member for grinding asurface, fluid pressure means operable to urge the member toward andinto engagement with the surface to be ground and including a fluidpressure delivery conduit and a valve in the conduit, a measuringinstrument for controlling the operation of the abrading member, meansfor continuously urging the measuring instrument into contact with thesurface being ground, said means including a confined substantiallyincompressible liquid medium, and means operatively associated with saidvalve and with said liquid medium and responsive to the flow of thelatter resulting from the movement of the measuring instrument formoving the valve and thereby varying the amount of fluid pressure actingon the abrading member.

11. In a surface grinding device, an abrading member for grinding asurface, fluid pressure means operable to urge the member toward andinto engagement with the surface to be ground and including a fluidpressure delivery conduit and a valve in the conduit, a measuringinstrument for controlling the operation of the abrading member, meansfor continuously 'urging the measuring instrument into contact with thesu'rface being ground, said means includin a confined plurality ofspherical elements contactually engageable with one another to serve asa force transmitting medium, and means operatively associated with saidvalve and with said force transmitting medium and responsive to themovement of the latter resulting from the movement of the measuringinstrument for moving the valve and thereby varying the amount of fluidpressure acting an the abrading member.

12. In a surface grinding device, an abrading member for grinding asurface, fluid pressure means operable to urge the member toward andinto engagement with the surface to be ground and including a fluidpressure line and a valve in said line, means for controlling the valveand thereby the operation of the abrading member, said means including ameasuring instrument contactually engageable with the surface beingground and movable to follow the changes in the level of such surface asit is being ground, and a confined substantially incompressible mobilemedium forming an operative connection between the measuring instrumentand the valve and rend'ering the valve responsive to the movement of themedium resulting from the movement of the measuring instrument.

13. In a surface grinding device, means for urging an abrading membertoward and into engagement with the surface to be ground including aconduit for delivering fluid under pressure for effecting such movementof the abradin memher, a valve seat in the conduit past which the fluidunder pressure is delivered, a valve member engageable with the valveseat to cut on fluid flow in the conduit and movable away from the seatto permit fluid flow thereby, a sizing element arranged to contact thesurface being ground and being movable to follow the changes in thelevel of the surface as it is being ground, an operative connectionbetween the valve member and the sizing element and coupling the twotogether for joint movement such that when the sizing element moves tofollow the changing level 'of the surface being ground the valve membermoves toward the valve seat and finally into engagement therewith, andcontrol means for modifying said operative connection to vary the extentof such movement of the sizing element be- 'fore the valve memberengages the seat.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,733,019 Johnson Nov. 25, 1930 2,195,055 Wallace l Mar. 26,1940 2,257,474 McKeon Sept, 30, 1941 2,320,747 Peterson et a l. l June1, 1943

